A better system for aircraft de-icing

The EU-funded ON-WINGS project has tackled the dangerous effects of ice on aircraft surfaces, a phenomenon that is becoming more common as air traffic increases. The result is a new and more efficient de-icing system that is better suited to next-generation composite airframe structures.

A better system for aircraft de-icing

The EU-funded ON-WINGS project has tackled the dangerous effects of ice on aircraft surfaces, a phenomenon that is becoming more common as air traffic increases. The result is a new and more efficient de-icing system that is better suited to next-generation composite airframe structures.

When an aircraft flies in cold, moist air, especially at low altitudes, ice can form rapidly, both on and behind the leading edge of aerofoils and other structures. This ice can disturb airflow and radically alter lift characteristics and hence aircraft handling.

Aircraft icing can be extremely dangerous and lead to fatal accidents. Furthermore, the problem is increasing as airport capacity is pushed to the limit, because aircraft are spending more and more time in low-altitude holding patterns.

Large aircraft use heat diverted from the engines to remove ice from flight-critical surfaces, while smaller aircraft sometimes use pneumatic boots that expand under pressure to shed the ice layers. But these technologies are not compatible with the new generation of air-transport vehicles in which composite materials are being used more extensively.

“As the industry drives towards more efficient and safer aircraft, there is a need to develop ice protection technologies that function effectively with new airframe structures and materials,” explains John Mudway of GKN Aerospace. “Airlines, aircraft operators and pilots would all benefit from this kind of development, which would deliver more controllable in-flight ice protection, lower fuel consumption and reduced aircraft emissions.”

Complex problem

Mudway says current ice detectors are not sensitive enough to distinguish different types of ice and are not located within the safety critical zones. Building on electrothermal de-icing technology now widely used in helicopters, the ON-WINGS project, which GKN Aerospace coordinates, has developed a smart, autonomous, composite, electrothermal de-icing system for fixed-wing, helicopter rotor-blade and engine-inlet applications.

“There are three significant technological outcomes from this project,” Mudway explains. “First, we have developed a novel fibre-optic sensor head. Next, we have a new signal-processing technology that can determine what type of ice is forming, including so-called ‘supercooled large droplets’ and mixed-phase ice, while accurately measuring its thickness. And finally, we have integrated this monitoring technology into the electrothermal ice protection system, where it directly controls a series of heater blankets, ensuring optimum de-icing performance while minimising power demand.”

ON-WINGS brought together the major European aircraft and helicopter manufacturers, specialist SMEs and research institutes to work on what Mudway says is a critical safety issue that crosses national and company boundaries.

“This project is a clear example of the real benefits to be gained from effective international co-operation. No single organisation within the ON-WINGS consortium could have developed this technology alone. Undoubtedly, progress would have been achieved by each of us individually, but it would have taken place at a much slower pace and the vital benefits we will reap would have taken much longer to achieve.”

And about EU support, Mudway acknowledges: “The support from the EU gave us the sound framework to form an effective consortium and the financial assistance to enable a diverse group of organisations – including SME-level companies – to combine forces to carry out innovative research and development work.”